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[英]Joining two different tables with a common third table on a common column
[英]Joining two tables with no common column
我想将两个表连接在一起,组合表1中的两个字段以形成组合键,并组合表2中的两个字段以形成组合键。
因为在ETL中表被截断,所以将删除主键
CREATE TABLE collection]
(
collectionid INT NOT NULL PRIMARY KEY,
spaceid INT NOT NULL,
collectionpa VARCHAR(150) NOT NULL,
collectionto VARCHAR (150) NOT NULL
)
CREATE TABLE objects
(
birstobj INT NOT NULL PRIMARY KEY
birstspace INT NOT NULL,
collectionid INT NOT NULL,
object_nm VARCHAR(150) NOT NULL,
object_label VARCHAR (150)NOT NULL
)
表1 spaceid和collectionpa中的组合键表2 birstspace和collectionid中的组合键
连接条件与任何其他SQL条件一样-您可以在此处使用两列:
SELECT *
FROM collection c
JOIN object o ON c.collectionid = o.collectionid AND
c.spaceid = o.birstspace
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